Driving mechanism for the loop-taking hook in lockstitch sewing machines



mmf. 118, 11924..

J. ,QQOPER DRIVING MECHANISM FOR THE LOOP TAKING HOOK IN LOCKSTIT'CHSEWING MACHINES Filed April ,25, 19:22

Patented Nov. lg, igZla JOSEPH GOOPER, OF ASHTON-UNDERLYNE, ENGLAND.

DRIVING MECHANISM FOR THE LOOP-TAKING HOOK IN LOCKSTITCH SEWINGMACHINES.

Application tiled April 25, 1922.

T all whom t may concern:

Be it known that I, JOSEPH Coornn, a subject of the King of GreatBritain and Ireland, and a resident of Ashton-under-Lyne,

in the county of Lancaster, England, have invented a certain new orImproved Driving Mechanism for the Loop-Taking I-Iook in LockstitchSewing Machines, of which the following is a specification.

In sewing machines having a rotary hook which engages the needle threadloop to spread the same around the casing containing the underthread, ithas lbeen eustomary with hooks rotating around a vertical axis to rotatethe said hook by means of a bottom shaft to which rotation was impartedfrom the top or driving shaft vof the machine through a crank or cranks,bevel or other gearing being interposed between the bottom shaft and therotating member which is formed with or which bears the hook. The resulthas been that when the inevitable wear took place in the variousbearings and gear teeth, the stitch became irregular, `and the timingVof the machine, that is, the correct relation of the movements of thehook, the needle, and the take up lever-which are of course all driven Afrom the top shaft of the machine-was no 0 `longer maintained, and theseparts did not act in unison for the correct formation of the stitch.Further the manufacture and machining and assembly ofthe various partshas been found extremely expensive.

The present invention relates to an improved driving mechanism for therotary hook in such sewing machines, and which mechanism, whilst simplein construction, and inexpensive, will obviate the difficulties hithertoexperienced and as mentioned above. In carrying it into effect I providedriving mechanism for arotary hook which has motion around a verticalaxis, and which driving mechanismeomprises a bottom shaft pivoted aboutmidway of its length to a link which is itself pivoted to the underfaceof the sewing machineplate. The bottom shaft is `therefore capable ofrocking motion` around its own centre and at the same time capable oflnotion around the' supporting center of the swinging link, that is,approximately, in the direction of its own length. Means are providedfor giving the bottom shaft these two motions simultanew ously, from thetop shaft of the sewing ma- Serial No. 556,556.

chine, the resultant of the said motions being that a rotary motion isgiven to auf,r point of the bottom shaft and consequently to the rotaryhook member which is suitably connected to one end of the bottom shaft.

The drive is Suitable for a rotary lock stitch sewing machine in whichan ordinary spool, specially wound, is used for the underthread, or in amachine of that type known as the two reel. .or twin bobbin wherein areel or cheese of thread as it comes fromthe manufacturer is used in asuitable casing for the underthread.

A convenient method of carrying the in.- vention into effect will now bedescribed with reference to the accompanying drawings, wherein z-fFigure 1 is a front elevation of a sewing machine showing the improveddrivey as ap; plied thereto; l

Figure 2 is an end view, looking from the left, of part of the mechanismshown in Figure l;

Figure 3 is a bottom plan ofthe sewing machine showing that part of themechanism which is below the bedplate of the machine in one position;and

Figure l is a similar view of the same mechanism in another position.

In the drawings, which are to scale, only so much .of the sewing machinearm is shown as is required for the purpose of description of theimproved drive.

Referring to the figures, l is the arm of the machine, and 2 thebedplate. 3 is the top or driving shaft driven by hand o r power throughthe balance wheel 4.. 5 is the needle shaft as usual.

6, 7, are drums which are fitted eccentrically upon the top shaft 3 toact as face cams-@their degree of eccentricity to` the axis of the saidtop shaft 3 being equaland occupying a position relative to each otheras shown in Figures 1 and 2. 8 and 9 are driving levers, bifurcated attheir upper extremities as shownv clearly in Figure 2, the bifurcatedends of these levers embracing the eccentric drums 6 and 7 as shown inthat figure. A central bearing shaft l0 is provided within the arm ofthe machine, its ends being fitted therein as shown or in any convenientmanner, the levers 8 and 9 being adapted to oscillate freely on the saidshaft by means of the bush bearings 11 and 12 to which Ibushes thesaiollevers .are secured.

tation ofthe top shaft will thus, through the drums 6 and 7, give avibratory motion to both levers 8 and 9 around their centres 10.Suitable oil holes" may be provided in the bushes 11 and 12.

13 is' the bottom shaft of the machine which gives motion to the member14' on which the loop takingl hook 15 is formed. TheV said bottom shaftis bifurcated or slotted to provide arms as shown at 16, 17 to formaslide or guide for the slide block 18, the sliding faces of which aremachined to'form an accurate and at the same time easy sliding tit'within the slide. The eentre portion of the slide block 18 is sphericaland forms a bearing for the end of lever 9 as shown by Figures 1 and 3,and the lower eX- tremity of the rocking lever 9 lits therein insuch amanner that whilst slight movement of the said extremity is permittedwithin' the spherical' portion ofthe slide member, there is' noylooseness of the said lever extremity within the said spherical bearing.y

The bottom shaft 13 is pivoted at 19'by means of a stud as shown to theextremity of a link 20 which is itself pivoted at 21 by means of a studto the underface ofthe bedvplate 2 ofthe machine. This link 2O ispivoted as shown, to the bedplate, viz: about midway of its length, andto the other end thereof is pivotally secured at 22 the lever 23, whichlatter is provided at its other eX- tremity with a bearing 24 for thelower end of the oscillating lever 8. The bearing 24 may be similar tothe bearing in the slide block 18. Y

The bottom shaft 13 is cranked at 25 to allow of that end thereof whichis to drive the vrotary hook to engage, by means of a socket bearing 26,with a -stud 27 secured in a short link28, the other endl whereof is vpivoted at 29 upon a crank pin of a crank piece 3,0 formed solid withthe circular block member31 which is adapted to support the rotarymember 14 which bears or has formed thereon the rotary hook 15. Othercrank means may however be employed to communicate the motion of shaft13 to therotary hook 15.

Assuming thatV the bottom shaft is in the position shown in Figure 3 andconsidering the Figures 1 and 2, it will beseen that when the shaft 3 isrotated in a clockwise direction, as viewed from the view point ofFigure 2, the cams 6 and7 will in their rotation causethe levers 8 and 9to oscillate upon the bearing 10. by reason of the engagement of theupper bifurcated ends of the said levers with the cams 6 and 7. Thebifurcated arms aremade an easy sliding lit upon the faces of the cams 6and 7 and are always in contact therewith. The eifect of thisoscillatory motion of the lever 9, the lower end whereof is fittedwithin the bearing of the slide block 18, is to cause this slide blockto move transversely7 to the bottom shaft 13 and describe a shallow arc,butI as the said slide block is a sliding lit within the slide recess1(3-417 (Figures 3 and 4) the bottom shaft 3 is constrained to moveradially around its pivotal point 19 with continued movement of thelever 9, the slide block 18 displacing itself longitudinally to thebottom shaft 13 within the recess 16-1T, as the said bottom shaft movesaround its centre. At the same time the lever 8 through the link 23rocks the link 2O around its pivotal point' 21, with the result' thatthe bottom shaft 13 not only has a radial movement around its pivotalpoint 19, but at the same time through the displacen'ient of the lever23 by the movement of lever 8 the point 19 moves a number of degrees ofarc, of which arc the point 21 is the centre. These movements takingplace simultaneously, the various members will assume the position shownin Figure 4,

from which it will be seen that the crank 30 has moved 90 degrees of itscomplete revolution. Movement of the levers 8 and 9 and their connectedparts continuing, one revolution of the crank 30 will take place,through the intermediary of the connecting members and the bottom shaft13 when the levers 8 and 9 have each effected one complete vibration ordouble oscillation around their centre 10.

The relative positions shown in the drawings ofthe rocking levers 8 and9 are those I have found in practice suitable to give the effectdesired, that is to say,V the locum eX- tremity of the lever 8 lagsbehind that ofthe locum end of lever 9 in its traverse in bothdirections. I do not however confine myself to the exact relation shownshould any variation in special circumstances be found expedient.Further, the relative dimensions of the various members comprising thcmechanism may be varied if :found necessary or desirable for anyparticular' purpose, without departing from the spirit of my invention.

As will be seen, the mechanism above described is not only simple inconstruction, but its nature permits of all of its members beingconstructed in cast iron, with a minimum of machining and consequentlessening of cost as compared to hitherto employed driving means forrotary hooks'.

I claim:

1. Improved driving means for the rotary loop taking hook of aloekstitch sewing machine, comprising a cam on the top shaft, anoscillating lever actuated by said cam and imparting oscillatory motionto a pivi oted lever which bears the pivoting means for the bottom shaftof the machine, and thus giving oscillating motion to the whole of thesaid bottom shaft, and a similar oscillating lever similarly actuatedthe lower end of which slides in a recess in the 'free end of the bottomshaft and gives oscillatory motion to the latter around its own pivotalcentre, for the purpose set forth.

2. Improved driving means for the rotary loop taking hook of alockstitch sewing machine, comprising a cam on the top shaft, anoscillating lever actuated by said cam and imparting oscillatory motionto a pivoted lever which bears the pivoting means for the bottom shaftof the machine, and thus giving oscillating motion to the whole of thesaid bottom shaft, a similar oscillating lever similarly actuated thelower end of which slides in a recess in the tree end of the bottomsha-ft and gives oscillatory motion to the latter around its own pivotalcentre, a rotary member bearing the loop taking hook, a supportingmember for the said rotary member, said supporting member having a crankformed solid therewith, and a pivoted link connecting the crank and thebottom shaft.

3. Improved driving means for the rotary loop taking hook of alockstitch sewing machine, comprising two cams mounted on the top shaftof the sewing machine, two levers each of which is bifurcated at itsupper end, and the said upper end embracing one of the cams, a bearingwithin the sewing machine arm on which bearing the two levers areadapted to oscillate in parallel planes, a lever pivoted upon the bottomplate of the machine and pivotally connected to the lower end of one ofthe said oscillatory levers, and a bottom shaft pivotally carried by thelever pivoted upon the bottom plate and having a recess in one endthereotl in which recess the lower end of the other bifurcated leverslidably fits to give oscillatory motion to the bottom shaft around itspivotal centre.

In testimony whereof I have hereunto set my hand.

JOSEPH COOPER.

